Surgical fasteners are widely used in many different procedures. For example, staples, sutures, clips and other fasteners are commonly used in laparoscopic and open surgical procedures to secure together two or more portions of approximated tissue, or to attach a prosthetic repair fabric, such as surgical mesh fabric, to tissue surrounding a defect as in a hernia repair operation.
Instruments for applying surgical fasteners typically include an elongated shaft that extends away from a handle end. A slender shaft profile may be desired to provide handleability and ease of use, as well as to ensure compatibility with the 5 mm and smaller trocars used in various laparoscopic procedures. Another design criteria is to increase the space within the shaft that accommodates the internal workings of the instrument, such as the surgical fastener delivery system, but without enlarging the overall shaft profile. A common approach for achieving both of these objectives is to reduce the wall thickness of the shaft; the outer profile is unchanged while the inner diameter of the shaft is increased.
To manipulate tissue or to otherwise effect the surgical site, the physician may lever or angle the thin walled, elongated instrument and, at times, may apply considerable force from the handle end to the remotely located distal end. Should excessive levels of force be applied, there may be a potential for the thin walled shaft to permanently bend or otherwise deform, or at least to deflect inwardly so as to interfere with the internal components of the instrument, such as the surgical fastener deliver system. Certain surgical fastener delivery instruments include cut-outs, reliefs, or other modifications in the wall structure of the elongated shaft, and the inventors have discovered that these wall structure modifications may be susceptible to a permanent bend or inward distortion in response to excessive forces applied to the instrument, particularly if the instrument is being levered or angled against a trocar through which the instrument has been inserted to reach the surgical site.